Fuel pressure regulator having offset head and orifice axes

ABSTRACT

A fuel pressure regulator including a valve head having a centerline offset from the centerline of a corresponding fuel orifice. The valve head may be offset with respect to the valve seat and orifice, the orifice may be offset within the seat with respect to the head and diaphragm assembly, or the axes of the head and seat may be non-coaxially biased. Because the vector of the valve closing force does not align with the centerline of the valve head and diaphragm assembly, a resulting torque on the valve head keeps the head in a stable, pivoted position at all flow rates. The valve head always makes contact with the valve seat at a predetermined point during regulator operation, eliminating pressure instabilities and noise experienced in prior art pressure regulators.

TECHNICAL FIELD

The present invention relates to fuel supply systems for internalcombustion engines; more particularly, to devices for controlling fuelsupply pressure; and most particularly, to a fuel pressure regulatorwherein a valve and diaphragm assembly is axially offset from a valveseat orifice to prevent large hysteresis values and audible noise.

BACKGROUND OF THE INVENTION

Fuel supply systems for internal combustion engines are well known andtypically include means for maintaining a predetermined inline pressureof fuel being supplied to fuel injectors or carburetors or the like. Aprior art fuel pressure regulator typically includes a valve having amatable seat and head. The valve seat includes a center-aligned fuelorifice. The fuel orifice is aligned with the centerline of the valvehead, which causes the resulting opening and closing forces to bealigned on the same centerline, desirably providing a force balance tothe regulator and intending to maintain a parallel orientation betweenthe valve head and the seat. The valve head is generally pawn-shaped andincludes a ball mounted on a stem and pivotably captured in a fixedretainer. Because the ball may swivel in the retainer, the valve head isundesirably responsive to flow cavitation turbulence occurring in thefuel orifice, resulting in valve vibration and audible noise (valvechatter). Because of this chaotic instability, the valve head sealingsurface either can remain parallel to the valve seat sealing surface orcan settle on the edge of the seat sealing surface at any one of aninfinite number of angular positions. Because of minute pressurefluctuations on the sealing surface of the valve head, caused bycavitation, the valve head tends to flutter among ever-changing restpoints on the seat. If the valve head does pivot and thereby remains incontact with the seat as flow rate is decreasing, the pressure at theset point flow rate will be significantly less than the actualincreasing flow rate value (flow hysteresis). Audible noise and largehysteresis values can affect user satisfaction and also causemanufacturing problems and high reject rates.

What is needed is a fuel pressure regulator which is silent and lacksflow hysteresis.

It is a principal object of the present invention to provide an improvedfuel pressure regulator wherein a valve head has a single and preferredmating position with a valve seat.

It is a further object of the invention to provide such a regulatorwhich is simple and inexpensive to manufacture.

It is a still further object of the invention to reduce themanufacturing cost and waste for fuel pressure regulators.

SUMMARY OF THE INVENTION

Briefly described, a fuel pressure regulator in accordance with theinvention includes a valve head and diaphragm assembly having acenterline offset from the centerline of a corresponding valve seat andfuel orifice. This may be accomplished either by offsetting the valvehead and diaphragm assembly in the pressure regulator with respect tothe seat and orifice, by offsetting the orifice in the seat with respectto the head and diaphragm assembly, or by inducing offsetting axesbetween the valve head and seat orifice.

The pressure differential between the control pressure above the valveand the backpressure on the fuel orifice results in a closing force thatacts along the centerline of the fuel orifice. Since the vector of thisforce does not align with the centerline of the valve head and diaphragmassembly, a torque on the valve head is always present which acts on thevalve swivel point to keep the valve in a stable, pivoted position atall flow rates. The valve head always makes contact with the valve seatalong the sealing surface edge at the contact point having the shortestdistance to the seat orifice centerline. Because the valve headmaintains this single point contact during regulator operation, thepressure instability and noise problems are eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is an elevational cross-sectional view of a prior art fuelpressure regulator;

FIG. 2 is an elevational schematic view showing the relationship of thevalve seat and valve head in a regulating valve assembly of the priorart regulator shown in FIG. 1;

FIG. 3 is an elevational schematic view of a first embodiment of aregulating valve assembly in accordance with the invention;

FIG. 4 is an elevational cross-sectional view of a portion of a fuelpressure regulator showing a second embodiment in accordance with theinvention;

FIG. 5 is a plan view of the diaphragm shown in FIG. 4;

FIG. 6 is an elevational schematic view of a third embodiment of aregulating valve assembly in accordance with the invention;

FIG. 7 is elevational schematic view of a fourth embodiment of aregulating valve assembly in accordance with the invention;

FIG. 8 is an elevational cross-sectional view of a fuel pressureregulator incorporating a fifth embodiment in accordance with theinvention;

FIG. 9 is an elevational cross-sectional view of a fuel pressureregulator incorporating a sixth embodiment in accordance with theinvention;

FIG. 10 is a plan view of the spring member shown in FIG. 9; and

FIG. 11 is a side view if the spring member shown in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The benefits and advantages of a fuel pressure regulator in accordancewith the invention may be better appreciated by first considering aprior art fuel pressure regulator.

Referring to FIGS. 1 and 2, a prior art fuel pressure regulator 10comprises a lower shell 12 and an upper shell 14 having a manifoldconnection arm 16. Lower shell 12 includes a first flanged lip 18. Adiaphragm retainer 20 is disposed within upper shell 14 and includes asecond flanged lip 22. A flexible diaphragm 24 is disposed at its outeredge between first and second lips 18,22 and is captured therebetweenvia a rolled edge 26 of upper shell 14 which also serves to close andseal the assembly.

Axially disposed in a tubular process 28 of lower shell 12 is a valveseat 30 having a fuel orifice 32 centrally formed therein along seataxis 34 thereby having an orifice axis coincident therewith. Seat 30 hasa first axial sealing surface 36 substantially orthogonal to axis 34.

Diaphragm 24 is provided with an aperture 38 having a diaphragm axiscoaxial with seat axis 34. Disposed coaxially and sealingly withindiaphragm aperture 38 is a valve retainer 42 having a typically conicalsocket 44 for retaining a ball end 46 of a valve head 48. Valve head 48,having axis 40 coaxial with the diaphragm axis, includes a flange 50having a second axial sealing surface 51 for variably mating with firstaxial sealing surface 36 to regulate flow of fuel through orifice 32.

A pressure regulating spring 52 is compressibly disposed between a lowerspring retainer 53 and an upper spring retainer 54 for urging secondsealing surface 51 toward first sealing surface 36, lower retainer 53being seated against diaphragm 24 to retain and seal the diaphragmagainst valve retainer 42. Upper spring retainer 54 is formed having acentral well 56 for slidingly engaging a tubular process 58 formed inupper shell 14. An adjustment screw 60 in process 58 engages retainer 54to adjust the axial position thereof and thus the compression of spring50 and the pressure required for fuel to displace head 48 from seat 30.

As noted above, because head 48 and seat 30 are coaxially disposed inthe prior art regulating valve assembly 39 (FIG. 2), and because headball 46 is rotatably retained in retainer 42, head sealing surface 51may engage seat sealing surface 36 at an infinite number of points alongthe periphery of seat sealing surface 36, none of which is preferred.Thus the motion of head 48 with respect to seat 30 can be chaotic duringflow of fuel therebetween.

Referring to FIG. 3, regulating valve assembly 39′ includes a firstembodiment in accordance with the invention. Head 48 and seat 30 areformed as in the prior art, as shown in FIGS. 1 and 2; however, theprocess 28′ is formed off-center in lower shell 12′ such that seatorifice axis 34 is not coaxial with head axis 40. When the axis of thevalve head is offset from the axis of the seat orifice, the valve headhas only one stable rest point on the seat. This is because the forcesacting on the valve to close the valve are not on the same axis as thevalve ball pivot point 61. The closing force is created by the localpressure drop at the seat orifice 32. The valve head always makescontact with the seat sealing surface 36 at the point 62 on the headsealing surface 51 closest to orifice 32. Since the vector of this forcedoes not align with the valve's pivot axis, a torque always acts on thepivot point to keep the valve in contact with the seat. Thus, the motionof the head with respect to the seat is non-chaotic.

Referring to FIGS. 4 and 5, in a second embodiment of a regulating valveassembly 39″, the valve head 48 and valve seat 30 may be axially offsetin accordance with the invention by forming aperture 38 and axis 40 indiaphragm 24 off-center from seat and fuel orifice axis 34, thusdisplacing head 48 and head axis 40. Again, during operation, the headand seat are in continuous contact only at point 62.

Referring to FIGS. 6 and 7, the axes may be offset in accordance withthe invention by coaxially aligning head axis 40 and seat axis 34 asshown in prior art 30 FIG. 1 but providing fuel orifice 32′ off-centerin seat 30 at a displaced orifice axis 34′. Axis 34′ may be parallelwith axis 40, as shown in third embodiment 39′″ (FIG. 6), or inclined toaxis 40 at an included angle θ, as shown in fourth embodiment 39″″ (FIG.7).

Referring to FIG. 8, an improved fuel pressure regulator 10′ inaccordance with the invention exemplarily incorporates fifth embodiment39′″″ of a regulating valve assembly. A blind axial bore 70 in seat 30extending into seat 30 from end 72 along axis 34 is intersected by asecond bore 74 extending from the opposite end of seat 30 along axis34′.

Referring to FIGS. 9, 10 and 11, fuel pressure regulator 110 inaccordance with the invention incorporates sixth embodiment 139 of aregulating valve assembly. In this embodiment, head flange 50, seatorifice 32, and seat 30 are formed as in the prior art. However, springmember 241 biasly tips head 48 relative to seat 30 so that, as can beenseen in FIG. 9, as head 48 approaches sealing contact with axial seatingsurface 36, head 48 always makes first contact with point 62 on surface36.

Spring member 141, includes outer hoop portion 142, which is generallycircular in shape, and crescent portion 144. Crescent portion 144includes base 146, arm 148 and end 150. As can be seen in FIG. 11, arm148 and end 150 are preferably on the same plane while base 146 and hoopportion 142 relative to arm 148 and end 150 are off-plane byapproximately, for example, in the range of preferably 5-10 degrees.Outer hoop portion 142 and crescent portion 144 are formed preferablyfrom spring steel. Crescent portion 144 is positioned relative to hoopportion 142 so that, when assembled as shown in FIG. 9, and when centerpoint 143 of outer hoop portion 142 coincides with seat axis 34, arm 148and end 150 of crescent portion 144 loosely captures neck 45 of valve48. In this position, crescent portion 144 is fixed to hoop portion 142by, for example, spot welds 152.

As best shown in FIG. 9, with spring member 141 assembled as shown, head48 always makes first contact with point 62 on surface 36. Thus, thevalve has only one stable rest point on the seat and the motion of thehead with respect to the seat is predictable and non-chaotic.

While biasing spring 141 shown in FIG. 9 is described as being formedfrom flat spring steel, it is contemplated that the biasing spring maybe formed from a polymer material or from various other materialsincluding spring wire.

While the invention has been described by reference to various specificembodiments, it should be understood that numerous changes may be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedescribed embodiments, but will have full scope defined by the languageof the following claims.

1. Apparatus for regulating inline pressure of a liquid flowing throughthe apparatus, the apparatus including a valve and comprising: a) avalve seat having a sealing surface with an edge and a flow orificetherethrough, said orifice having an orifice axis; and b) a valve headhaving a surface matable with said valve seat sealing surface and havinga valve head axis, wherein said orifice axis and said valve head axisare non-coaxial, with a point on said sealing surface edge closest tosaid orifice axis of said valve seat establishing a single point ofcontact with said valve head surface.
 12. A method for preventingchaotic flow in an apparatus for regulating inline pressure of a liquidflowing through the apparatus, the apparatus including a valve seathaving a flow orifice therethrough, said orifice having an orifice axis,and a valve head matable with said valve seat and having a valve headaxis, comprising the steps of: a) forming a first mating surface on saidvalve head in a plane orthogonal to said valve head axis; and b) forminga second mating sealing surface having an edge on said valve seatadjacent said first mating surface, wherein said orifice axis and saidvalve head axis are non-coaxial so that a point on said sealing surfaceedge closest to said orifice axis of said valve seat establishes asingle point of contact with said valve head surface.